This is a 2 pack of filters Pleatco: PGS25P4 | Unicel: 4CH-24 | Filbur: FC-0131 Diameter: 4 5/8" Length: 9 3/4" Top: Handle Bottom: 1 1/2" MPT Threaded Filter Area: 25 sq ft Filter Material: reemay 3oz material Alternate Filter Names: 20254-238 | 17-175-1265 | APC 12519 | 212321 | 17-175-1264 | 373005 | PTL 20HS W/ PAD | PTL20HS W/ PAD AD | PTL 20HS | PGS25 W/ PAD | PTL20HS-P4 | PAQ25N | PAQ25-N Used in pools / spas made by: Advanced Spa Design | After Hours Spas | American Dream | Aqua Spa | Blue Ridge Spas | CTA Spas | DM Industries | Dream Maker Spas | Echo Series | Ft Wayne Spas | Gatsby | Heartland Spas | Hydro Spa | Icon Spas | Image Spas | Imperial Spas | Keyes Spas | La Spas | Lowes | Lumi-O | Maax Spas of AZ | Mountain Meadows Spa | Mountain Mist Spa | Mountain Springs Spa | Mountain Stream Spa | Nemco | Saratoga Spas | Softub | Vita Spas | Weslo | White Springs Spas and other manufacturers